These studies are directed towards elucidating the molecular basis of glycogen synthase activity in liver. We have measured the number of phosphates in endogenous synthase D and synthase I. We will do structural studies to find the location of these phosphates and how they correspond with the phosphates put on in vitro by purified kinases. We have completely separated synthase D from synthase I and studied their kinetic properties. We will compare the properties of these purified enzymes with enzymes in situ, i.e. in a "leaky" cell preparation. We shall prepare antibodies to purifed rat synthase D and use them to study in vivo phosphorylation.